[MQP] Enhancing Chilled Water Distribution

Sponsor: Panama Canal Authority
Student Team: Keith Steven Black
Mario Duane Edward Reed
Abstract: The Panama Canal Authority (ACP) uses an electric vapor compression chilling water distribution method to cool their facilities in the Balboa area. In preparation of the possibility of a relocation of facilities, the ACP is looking for alternatives to replace this existing 60-year-old plant. A notable alternative was proposed in previous years that evaluated the desirability of a central system of chilled water in Balboa and later the alternative of producing cold water by co-generation with excess heat emitted from the Mira Flores power plant.
Links: Final Report

Executive Summary

The Panama Canal Authority contributes more to the country of Panama than just provide administration for the Canal. The ACP supplies a great deal of the chilled water supply for air-conditioning units in the Balboa and Corozal areas. From clientele outside of the ACP to multiple buildings on the ACP campus, the chilled water distribution supplied is of great importance. As you can imagine, in such a warm climate, air-conditioning is extremely important. The main chilled water facility currently in use is in the Balboa area. This facility currently houses outdated machinery and equipment. The cooling towers outside the facility are over 50 years old and are constructed with currently outdated material. If the ACP wants to remain a beacon of sustainable energy, then an analysis of new alternatives needs to be conducted.

Co-generation is a process that takes advantage of waste-heat, and converts it into raw energy. The ACP has a thermoelectric power plant in Mira Flores that emits a great deal of waste heat into the atmosphere. In order for the waste heat to be advantageous, an absorption chiller must be put in place. Absorption chillers physically take the heat, usually steam, emitted from the power plant and convert the steam , using thermodynamic properties of water, to chill water for the airconditioning units. In our case, chilled water generated through co-generation at Miraflores will traverse through a pipeline from Miraflores to Balboa, approximately 6 kilometers in length.

This project aimed to evaluate the feasibility of implementing such a pipeline from Miraflores to Balboa. In addition, this project analyzed another alternative scenario that calls for constructing a completely new electric chilling facility in the Balboa area that would serve the same purpose as the pipeline. Not only is the current electric system in Balboa outdated, but our hypothesis predicts that annual electricity expenses can almost be eliminated with the processes of cogeneration and absorption. Instead of paying for electricity to power the chillers, co-generation allows for energy to be generated through waste energy, therefore saving money. In order to evaluate our theory, we needed to research current flows and operations. Site assessments and Supervisor interviews were conducted to obtain the information we needed. We generated a flow model to desirable ACP specifications, including pipe size; pump power, and storage tank volume. Once the most cost and energy efficient method was chosen, an economic analysis was performed.

Economic analysis model calculations take an investment value, annual expense values, and yearly income and compound the rate of return over the next twenty years. One model was created to compare the co-generation scenario to the current systems and the new facility scenario to the current systems. An ultimate question to be answered was: would it more efficient to implement the co-generation line, or to invest in all aspects of a new facility? In our research we found that the new facility scenario returned a 12% value. In the midst of project planning we set a minimum acceptable rate of return (MARR) of 14%. With that said, the new facility scenario would in fact lose the ACP money over the next twenty years. When compared with the co-generation scenario, we found a return rate of 22%. The amount of energy saved each year was more than enough to overcome any investment costs and would allow the ACP to profit from such an expansion, not to mention profit from sales to potential clients located in the path of the pipeline. The co-generation pipeline proved to be more energy efficient by using waste heat to power a new system, so that less electricity will be used in their operation and more can be sold to the national market. Therefore our recommendation to the ACP is to further investigate the co-generation scenario and make a plan of action to implement this alternative to their current chilled water distribution methods.

The work done for the ACP has been in fulfillment of WPI’s Civil and Environmental Engineering Capstone design. The project scope included looking at economic feasibility, sustainability, the environment, and social implications. The economic portion of it came from analyzing all of the costs included in both alternative scenarios and assessing the feasibility of implementing these alternatives when compared to the current cost of operation. The sustainability and environment parts of the project were joined in one aspect of the project. This part was looking at the use of co-generation in conjunction with absorption chillers to use waste heat to provide the driving energy in the absorption process. This would be both environmentally conscious, and a good start to provide a sustainable base for the ACP’s operations. Finally social implications were taken into account by looking at the impact of construction that would result from the project, and what the affects would be in the local area due to the construction. Based on these different criteria we provided results and recommendations that we found to be most appropriate for the given problem.